1. Technical Field of the Invention
The present invention relates to a mobile telecommunications system and, in particular, to the remote retrieval of subscriber identity module (SIM) stored data via an over-the-air connection-less communications link.
2. Description of Related Art
With the introduction of the Global System for Mobile (GSM) communication and the Personal Communications System (PCS), a number of advanced subscriber features and applications are provided to mobile subscribers. One such feature is a Subscriber Identity Module (SIM) card attachable to a mobile station. Using an SIM card, a mobile subscriber is able to store necessary mobile subscriber information in a detachable memory unit and freely associate it with any available mobile station. Such information includes a mobile subscriber's Mobile Station Integrated Service Digital Network (MSISDN) number (more commonly known as a directory number), or other user specified information, such as preferred speed dialing lists or screening lists. By inserting a mobile subscriber's SIM card into a mobile station, the stored subscriber information in the inserted SIM card is available to the mobile subscriber's new terminal. As a result, the mobile subscriber is able to freely utilize any available mobile station while maintaining the same MSISDN number and subscriber feature data.
Another application is the communication of unstructured data between a mobile station and a serving mobile telecommunications network. Messages like Short Message Service (SMS) messages are utilized to communicate text data between a serving mobile switching center (MSC) and a mobile station. Using SMS messages, the serving MSC can transmit user information to the mobile station and have the mobile station store the received user information in an associated SIM card. SMS messages can then be used to update an SIM card with the latest menu options, speed dial lists, subscriber feature information, etc.
Another example of unstructured data communications comprises the Unstructured Supplementary Service Data (USSD) message. Using USSD messages, a mobile telecommunications network is able to transparently communicate text data with a mobile station. For example, a mobile station can receive and display text messages on an attached display unit and subsequently return a reply message back to the mobile network.
However, even though SMS and USSD messages can be utilized to communicate unstructured data between a mobile telecommunications network and a mobile station, there is currently no mechanism available to remotely request and retrieve SIM stored subscriber data by a mobile telecommunications network via an over-the-air communications link. A mobile network or another user connected to the mobile network has no mechanism to remotely access and retrieve the SIM stored information from the mobile station. As an illustration, even though a mobile subscriber can store his credit card information into his SIM card, whenever the mobile subscriber makes an airline reservation or purchases a product over the phone, the mobile subscriber has to manually and inconveniently enter a long series of credit card numbers to enable the seller to properly credit the subscriber's account.
Accordingly, there is a need to enable the mobile telecommunications network to remotely request and retrieve subscriber data stored in a particular SIM card associated with a mobile station via a connection-less communications link.